Muscle Strength Profiles According to Kidney Dysfunction and Anemia Status in Korean Adults Aged ≥40 Years: A Nationwide Cross-Sectional Study

Background/Objectives: Kidney dysfunction and anemia may each be associated with impaired muscle strength, but evidence on their concurrent presence is limited. We examined muscle strength according to kidney dysfunction and anemia status in Korean adults aged ≥40 years. Methods: This cross-sectional study used 2024 Korea National Health and Nutrition Examination Survey data. Kidney dysfunction was defined as estimated glomerular filtration rate < 60 mL/min/1.73 m2 or urinary albumin-to-creatinine ratio ≥ 30 mg/g; anemia as hemoglobin < 13 g/dL in men and <12 g/dL in women. Complex-sample logistic regression and general linear models analyzed 3649 participants in four groups. Results: Compared with participants with neither condition, the primary confounder-adjusted odds of low muscle strength were higher in the anemia-only group (adjusted odds ratio [aOR], 2.38; 95% confidence interval [CI], 1.57–3.61) and concurrent group (aOR, 3.31; 95% CI, 1.86–5.89), but not in the kidney dysfunction-only group (aOR, 1.42; 95% CI, 0.88–2.30). The concurrent group had the largest adjusted deficit in maximum handgrip strength (−2.51 kg; p < 0.001). Bonferroni-adjusted direct comparisons showed significantly poorer outcomes in the concurrent group than in the kidney dysfunction-only group, but not the anemia-only group. Conclusions: The concurrent presence of kidney dysfunction and anemia was associated with the least favorable muscle strength profile, particularly relative to kidney dysfunction alone; differences from anemia alone were not statistically significant after multiplicity correction.